A radium-226 nucleus contains 88 protons and 138 neutrons. It decays by emitting an α\alphaα-particle and becomes a nucleus of an isotope of radon. The symbol for radium is Ra\text{Ra}Ra and the symbol for radon is Rn\text{Rn}Rn.
Write down the nuclide equation for this decay.
Cesium-137 is radioactive with a half-life of 30 years. A soil sample contaminated during an accident is analyzed. The quantity of cesium-137 in the sample is 12.5%12.5\%12.5% of the quantity present immediately after the accident.
Calculate the time that has elapsed since the accident occurred.
484 exam-style questions on CIE IGCSE Physics 5.2 Radioactivity, covering 5.2.1 Background radiation and measuring count rate, 5.2.2a Alpha, beta and gamma emission, 5.2.2b Deflection and ionising effects of nuclear radiation, 5.2.3a Radioactive decay, 5.2.3b Effects of decay on the nucleus and decay equations, 5.2.4a Half-life, 5.2.4b Choosing isotopes for applications, and 5.2.5 Effects of ionising radiation and safety precautions. Each one has a worked solution and a mark scheme showing where the marks go.